In the building construction industry, a head-of-wall joint (also sometimes referred to as a top-of-wall joint) refers to the linear junction or interface existing between a top section of a wall assembly and the ceiling (where the ceiling may be a next-level flat concrete floor or a corrugated pan roof deck, for example). Similarly, an expansion joint refers to the linear junction existing between adjacent wall (or ceiling) sections (such as adjacent pieces of wallboard, for example). The proper sealing of linear junctions, including head-of-wall joints and expansion joints, during the building construction phase is critically important to prevent or reduce the spread of fire and smoke in the event of a building fire.
As appreciated by contractors in the building construction industry, there are two primary methods used for sealing linear junctions (e.g., head-of-wall joints and expansion joints) against the spread of fire and smoke; namely, (1) the application of a firestop intumescent sealant (in the form of either a caulk or spray) along and into the linear joint, or (2) the installation of specialty tracks and/or other suitable framing members that have a pre-applied intumescent tape appropriately placed on (i.e., in physical contact with) the track or other suitable framing member such that the intumescent tape seals the linear construction joint. These two known methods have both been tested and approved by Underwriter Laboratories, Inc. ((“UL”—an independent worldwide testing and regulatory compliance certification organization) as being compliant with certain specified fire and hose stream test standards presently in existence.
More specifically, UL has tested and certified various building construction “joint systems” in accordance with their testing standards as set forth in, for example, document “UL 2079 Tests for Fire Resistance of Building Joint Systems, fifth edition (Aug. 26, 2015).” These UL fire tests described here are applicable to building construction joint systems (assemblies) of various materials and construction (intended for use at linear junctions between adjacent fire resistive structures). UL's joint system fire tests are intended to evaluate the length of time that a specified joint system will contain a fire during a predetermined test exposure. UL's joint system fire tests evaluate the joint system's resistance to heat and, in some instances, to a hose stream, while carrying an applied load (if the assembly is load bearing). UL's joint system fire tests may, in some instances, include an air leakage test to determine the rate of air leakage through joint systems resulting from a specified air pressure difference applied across the surface of the joint system.
For example, and under current UL's requirements, a joint system may be subjected to a controlled fire exposure that achieves specified temperatures throughout a specified period. Some joint systems are cycled through their intended range of movement prior to fire exposure (to demonstrate that the joint system's range of movement and the impact of the joint system during movement on the adjacent fire resistive structures). Joint systems are often required to be loaded to their designed live load capacity during the fire test. For tests involving wall-to-wall and head-of-wall joint systems, the fire test is typically followed by a hose stream test. UL's joint system fire tests and related requirements are intended to provide a relative measure of fire performance of comparable assemblies under specified fire exposure conditions.
In the building construction industry, metal framing assemblies are commonly used to construct commercial and residential buildings. Metal framing assemblies are generally constructed from a plurality of metal framing members including studs, joists, trusses, and other metal posts and beams formed from sheet metal (and frequently fabricated to have the same general cross-sectional dimensions as standard wood members used for similar purposes). Metal framing members are typically constructed by either brake-pressing or roll-forming (with both methods being referred to as “cold-formed” processes) 12 to 24 gauge galvanized sheet steel. Although many cross-sectional shapes are available, the primary shapes used in building construction are C-shaped studs and U-shaped tracks. For example, most wall assemblies are made from opposing cold-formed slotted U-shaped tracks fastened to the floor and ceiling, and a plurality of a cold-formed C-shaped studs laterally spaced apart and positioned between the opposing tracks. Head-of-wall linear joints associated with these types of joint systems are of especially importance in terms of sealing against the spread of fire and smoke.
Although some progress has been made in recent years, there is still a need in the art for new and improved fire blocking sealant systems and methods—including innovative building construction specialty products that better seal linear construction joints (for purposes of impeding the transmission of fire and smoke in the event of a building fire). The present invention fulfills these needs and provides for further related advantages.